02 Jun 2017 --- A recent study at Sahlgrenska Academy and University of Girona indicates that the clinical effect of metformin is achieved through modulation of the gut microbiota, providing a clearer picture of how the classic diabetes medication works. The human body contains more bacteria than human cells. Most of these bacteria exist in the gut, which is the most densely populated ecosystem known today, where their genes (microbiome) complements our own genome with 1000-fold more genes.